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Full text of "IS 15835: Gaseous Fire Extinguishing Systems--HCFC-125 Extinguishing Systems"

**************** 




Disclosure to Promote the Right To Information 

Whereas the Parliament of India has set out to provide a practical regime of right to 
information for citizens to secure access to information under the control of public authorities, 
in order to promote transparency and accountability in the working of every public authority, 
and whereas the attached publication of the Bureau of Indian Standards is of particular interest 
to the public, particularly disadvantaged communities and those engaged in the pursuit of 
education and knowledge, the attached public safety standard is made available to promote the 
timely dissemination of this information in an accurate manner to the public. 




Mazdoor Kisan Shakti Sangathan 
"The Right to Information, The Right to Live'' 



IS 15835 (2009) : Gaseous Fire Extinguishing 

Systems — HCFC-125 Extinguishing Systems. ICS 13.220.10 




Jawaharlal Nehru 
'Step Out From the Old to the New" 



aj^&vi iJii^s:y>K^ isb^^ni^seg 



:<>5&i| mT'5K^5?::5:^>^i»l 



K^^^iXSVCd^ 



Satyanarayan Gangaram Pitroda 
Invent a New India Using Knowledge 



Bhartrhari — Nitisatakam 
''Knowledge is such a treasure which cannot be stolen" 




^'^^^r 



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1515835:2009 

M[^ 3tPH W^ WM— i^^RlVf^-125?FR q^gfem! 

Indian Standard 

GASEOUS FIRE EXTINGUISHING SYSTEMS — 
HCFC-125 EXTINGUISHING SYSTEMS 



ICS 13.220.10 



© BIS 2009 

BUREAU OF INDIAN STANDARDS 

MANAK BHAVAN, 9 BAHADUR SHAH ZAFAR MARG 

NEW DELHin 0002 



February 2009 Price Group 5 



Fire Fighting Sectional Committee, CED 22 



FOREWORD 

This Indian Standard was adopted by the Bureau of Indian Standards, after the draft finalized by the Fire Fighting 
Sectional Committee had been approved by the Civil Engineering Division Council. 

It is important that the fire protection of building or plant be considered as a whole. HCFC-125 total flooding 
systems form only a part, though an important one, of the available facilities. However, it should not be assumed 
that their adoption necessarily removes the need to consider supplementary measures, such as the provision of 
portable fire extinguisher or mobile appliances for first aid or emergency use, or measures to deal with special 
hazards. 

HCFC-125 is recognized as effective for extinguishing Class A, Class B and Class C fires and also where electrical 
risks are present. Nevertheless, it should not be forgotten in the planning of the comprehensive schemes that 
there may be hazards for which this technique is not suitable, or that, in certain circumstances or situation, there 
may be danger in its use, requiring special precautions. 

Advice on these matters can be obtained from organizations involved with the installation of HCFC-125 total 
flooding systems. The design and fabrication of the container shall be in accordance with the requirements of the 
Chief Controller of Explosives, Nagpur. 

In the formulation of this standard, assistance has been derived from ISO 14520-8 : 2006 'Gaseous fire extinguishing 
systems — Physical properties and system design ~— Part 8 : HCFC -125 Extinguishing systems'. 

For the purpose of deciding whether a particular requirement of this standard is complied with, the final value 
observed or calculated, expressing the result of a test or analysis, shall be rounded off in accordance with IS 2 : 1 960 
*Rules for rounding off numerical values (revisedy . The number of significant places retained in the rounded off 
value should he the same as that of specified value in tliis standard. 



AMENDMENT NO. 1 IVIAY 2010 
TO 
IS 1^^835 : 1009 GASEOUS FIRE EXTING WSHING ^ 
,3yI™S - HCFC-OS EXTINGUISHING SYSTEMS 

Substitute 'HFC 125', /or 'HCFC 125' wherever appears in the standard. 



(CED 22) 



Rii^ography Unit, B!S, New Delhi, India 



IS 15835 : 2009 



Indian Standard 

GASEOUS FIRE EXTINGUISHING SYSTEMS — 
HCFC4 25 EXTINGUISHING SYSTEMS 



1 SCOPE 

1.1 This standard sets out specific requirements for 
the design and installation of total flooding fire 
extinguishing systems employing HCFC-125 gas 
extinguishant. This standard is applicable to single 
supply as well as distributed supply systems. 

\.l i'his standard complements various general 
requirements applicable to all types of gaseous 
fire-extinguishing systems (Halocarbon as well as Inert 
^ systems) listed in IS 15493. As such, both these 
sf^f lards should be read together before designing a 
^^^tem. Where requirements in both the standards 
Jiffer, this standard shall take precedence. 

13 This standard covers total flooding systems of 
nCFC-25 operating at nominal pressures of 2.5 MPa 
dnd4.2MPaonlyat21°C. 

/REFERENCE 

I he standard listed below contains provision which 
... jugh reference in this text, constitutes provision of 
this standard. At the time of publication, the edition 
' dicated was valid. All standards are subject to 
levision and parties to agreements based on this 
standard is encouraged to investigate the possibility 
of applying the most recent edition of the standard 
indicated below: 

IS No. Title 

15493 : 2004 Gaseous fire extinguishing 
systems — General requirement 

3 GENERAL INFORMATION 

3,1 Application 

3.1.1 HCFC-125 total flooding system is designed to 
develop a controlled atmosphere in an enclosed space 
and extinguishes the fires by physically cooling the 
fuel and by breaking the free radical chain reaction 
and thereby interfering with the combustion process. 
The appropriate HCFC-125 concentration shall also 
be maintained until the temperature within the 
enclosure has fallen below the re-ignition point. 

3.L2 The minimum HCFC-125 concentration 
necessary to extinguish a flame has been determined 



by extensive experiments for several surface type fires 
particularly those involving flammable liquids and 
gases and polymeric materials. For deep-seated fires, 
longer soaking times may be necessary but are difficult 
to predict. 

3.1.3 It is important that concentrations are not only 
achieved but also maintained for a sufficient period o^ 
time to allow effective emergency action by trained 
personnel. This is equally important in all classes of 
fires since a persistent ignition source can lead to a 
recurrence of the initial event once the HCFC-125 has 
dissipated, 

4 GAS CHARACTERISTICS AND PROPERTIES 

4.1 HCFC-125 is a colourless, electrically non- 
conductive gas with a density approximately four times 
that of air. 

4.2 HCFC-125 total flooding systems can be used to 
extinguish all classes of fires. For Class C fires (fires 
involving gases), the risk of explosion after extinction 
should be studied with care. Information on use and 
limitations of HCFC-125 is available in IS 15493 
{see 1.2), 

4.3 Chemical formula of HCFC-125 gas is shown in 
Table 1 . 

Table 1 Composition of HCFC-125 Gas 

Clean Chemical Name Commercial 

Agent Name 

Formula 

(0 (2) (3) 

CHF2CF3 Penta fluoro ethane (99.85 percent) MCFC-l 25 



4 A HCFC-125 is a gas liquefied at suitable pressure 
and temperature that can be stored in a pressurized 
container. 

4.S HCFC-125 gas shall comply with specification as 
shown in Table 2. 

4M Physical properties of HCFC-125 gas is shown in 
Table 3. 

4.7 Toxicological information for HCFC-125 gas is 
shown in Tables 4 and 5. 



IS 15835 : 2009 



Table 2 Specification for HCFC-125 Gas 
(Clause 4.5) 



SI No. 

(1) 



Property 

(2) 



Requirement 

(3) 



i) Purity 99 percent by mole percent, A//« 

ii) Moisture, percent by weight, 0.001, Max 

Max 

iii) Acidity ppm by weight 3.0 

HCl equivalent, Max 

iv) Non-volatile residue 0.05 percent g/100 ml. Max 

Table 3 Physical Properties of HCFC-125 Gas 
(Clause 4,6) 



SI No. 
(1) 



Property 

(2) 



Value 

(3) 



i) 


Molecular mass 


120.02 


ii) 


Boiling point at 0. 1 MPa, °C 


-48.5 


iii) 


Freezing point, ""C 


- 102.8 


iv) 


Vapour pressure at 20°C, MPa 


1.21 


V) 


Specific volume of superheated vapour 
at0.1MPaand20°C(m'/kg) 


0.259 


vi) 


Critical temperature, °C 


66 


- vii) 


Critical pressure, MPa 


3.395 


viii) 


Critical volume, cc/mol 


210 


ix) 


Critical density, kg/m^ 


572 


X) 


Liquid density at 20X, kg/m^ 


1 218 


xi) 


Saturated vapour density at 20°C, kg/m^ 


76.92 




Table 4 Toxicological Information for 




HCFC^125 Gas 






(Clause 4.7) 





SI 

No. 

(1) 



Property 



(2) 



Value 
Percent 

(3) 



i) No observed adverse effect level (NO AEL) 7.5 

ii) Lowest observed adverse effect level (LOAEL) 10 

iii) Four hour lethal concentration LC50' >70 



Table 5 Time for Safe Human Exposure at Stated 

Concentration for HCFC-125 

(Clause 4,1) 



SI No. 


HCFC-125 Concentration 


Human Exposure Time 




^ 






mm 




'"Percent v/v 


ppm^ 




(1) 


(2) 


(3) 




(4) 


i) 


7.5 


75 000 




5 00 


ii) 


8.0 


80 000 




5 00 


iii) 


8.5 


85 000 




5 00 


iv) 


9.0 


90 000 




5 00 


V) 


9.5 


95 000 




5 00 


vi) 


10.0 


100 000 




5 00 


vii) 


10.5 


105 000 




5 00 


viii) 


11.0 


110 000 




5 00 


ix) 


11.5 


115 000 




5 00 


X) 


12.0 


120 000 




L67 


xi) 


12.5 


125 000 




0.59 


xii) 


13.0 


130 000 




0.54 


xiii) 


13.5 


135 000 




0.49 


NOTE 


; — Data derived from EPA approved 


and peer-reviewed 


PBPK model or its equipment. 







4,8 Container Characteristics 

The maximum fill density, container- working pressure 
of the HCFC-125 cylinders shall not exceed the values 
provided in Table 6 for systems operating at 2.5 MPa 
and 4.2 MPa respectively. 

Table 6 2.5 MPa and 4,2 MPa Storage Container 
Characteristics for HCFC-125 



SI No. 


Property 

(2) 


Value 


(1) 


2.5 MPa 
(3) 


4.2 MPa 
(4) 


i) 
ii) 

iii) 


Maximum fill density, kg/m^ 
Maximum container working 
pressure at 50°C, MPa 
Super pressurization at 20°C, 

MPa 


930 
4 

2.5 


930 

5.3 

4.2 



NOTES 

1 For further data on pressure/temperature relationship, Fig. 1 
and Fig. 2 should be referred. 

2 Exceeding the maximum fill density may result in the 
container becoming iiquid full'. With the result that an 
extremely high rise in pressure occurs with small increases in 
temperature that could adversely affect the integrity of the 
container assembly. 



4.9 Pressure versus Temperatures 

To allow faster flow through piping systems, the natural 
pressure of HCFC-125 is often supplemented with dry 
nitrogen. Commonly used pressures are respectively 
2.5 MPa and 4.2 MPa measured at 2rC. The respective 
vapour pressures of HCFC~125 as well as dry nitrogen 
vary with temperature. 

4.10 Nitrogen Super Pressurization 

Nitrogen is soluble in HCFC-125. Thus when a storage 
cylinder is pressurized with nitrogen, some dissolves 
in the liquid HCFC-125 and the rest remains in the 
vapour phase and combines with the vapour phase of 
HCFC-125 to produce the pressure necessary to propel 
the extinguishing agent HCFC-125 through the 
pipeline (see also Fig. 1 and Fig. 2). 

5 SAFETY OF PERSONNEL 
5,1 General 

a) Any hazard to personnel created by the 
discharge of HCFC-125 shall be given due 
consideration in the design of the system. 
Potential hazard can arise from the following: 

1) the extinguishant itself; 

2) the combustion products of the fire; and 

3) breakdown products of the extinguishant 
resulting from exposure to fire. 

b) In areas, where there is a likelihood of 
significant difference between gross and net 



IS 15835 : 2009 



a. 




929kg/m3 

- 897kg/m^ 

865 kg/m ^ 
833kg/m^ 

800 kg/m ^ 



-20 -10 10 20 30 40 50 60 70 80 90 
Temperature rC) 

Fig. 1 Temperature-Pressure Curve for 2.5 MPa at 2rc 



0) 
CL 




*- 929.1 kg/m^ 

896.4 kg/m ^ 

*^ 866.6 kg/m ^ 



-20 20 40 60 80 100 

Temperature fC) 
Fig. 2 Temperature-Pressure Curve for 4.2 MPa at 21''C 

3 



IS 15835: 2009 



volumes of the enclosure, utmost care shall 
be exercized in proper system design to ensure 
that maximum concentrations as detailed in 
7cl are not exceeded. 

1) Where design concentration exceeds the 
LOAEL,HCFC- 125 shall be used for 
total flooding only in normally un- 
occupied areas. For minimum safety 
requirements, see 5 of IS 15493. 

2) Toxicological information of HFC- 125 
is shown in Table 4. 

3) HCFC-125 system for spaces that are 
normally occupied and designed to 
concentrations above the NOAEL shall 
be permitted, if means are provided to 
limit exposure to the design 
concentrations shov^n in Table 5 that 
corresponds to a maximum permitted 
human exposure time of 5 min. 

5,2 Miscellaneous Hazards 

Some of the additional hazards are as below: 

a) Cold Temperatures — Direct contact with the 
vapourizing liquid being discharged from a 
HCFC- 1 25 nozzle will have a strong chilling 
effect on objects and can cause frostbite burns 
to the skin. The liquid phase vapourizes 
rapidly when mixed with air and thus limits 
the hazard to immediate vicinity of the 
discharge point. 

b) Visibility — Discharge of HCFC-125 may 
create a light mist resulting from condensation 
of moisture in the air. However, the mist rarely 
persists after the discharge is completed. Thus 
little hazard is created from the standpoint of 
reduced visibility. Once HCFC-125 is 
discharged into an enclosure, its presence is 
easy to detect through the normal senses in 
concentrations above about 3 percent. 

c) Uneven Distribution — In total flooding 
systems, the high density of HCFC-125 
vapour requires the use of discharge nozzles 
that will achieve a well-mixed atmosphere in 
order to prevent local pockets of higher 
concentration. HCFC-125 and HCFC-125 air 
mixtures are also denser than air and will drift 
and accumulate in low spaces, such as cellars, 
pits and floor voids, and may be difficult to 
ventilate effectively. 

6 VENTING ARRANGEMENT 

Venting shall be provided at levels as high as possible 
in the enclosure. Strength and allowable pressures for 
average enclosures shall be in conformity with the 



following guidelines. The building requirements for 
the type of enclosure and free venting required can 
also be calculated from the relevant specifications. 

7 EXTINGUISHING AGENT SUPPLY 



7.1 Quantity 

a) Quantity Requirements (Main) — The amount 
of the HCFC-125 in the system shall be at 
least sufficient for the largest single hazard 
protected or group of communicating hazards 
that are to be protected simultaneously. 

b) Quantity Requirements (Reserve) — Same 
quantity as that of main quantity requirements 
should be available as reserve. However, if 
the replenishing of agent supply takes more 
than 7 days at the site of installation, advice 
may be sought from the authority concerned 
on quantity to be kept available as reserve. 

c) Uninterrupted Protection — Reserve supply 
where provided and main supply should be 
permanently connected to the distribution 
piping and arranged for easy change-over to 
enable uninterrupted protection. 

d) The quantity of the HCFC-125 required shall 
be further adjusted to compensate for any 
special conditions, such as unclosable 
openings, forced ventilation, the free volume 
of air receivers that may discharge into the 
risk, altitude (substantially above or below sea 
level) or any other causes for the extinguishant 
loss. However in no case the design 
concentration of HCFC-125 shall exceed its 
LOAEL (5£e Tables 4 and 5) 

7.2 Total Flooding Quantity 

a) The amount of HCFC- 1 25 required to achieve 
the design concentration shall be calculated 
from the following equations and this figure 
shall need further adjustment as stated 
in7,l(d). 



M = 



VC 



s(ioo-c) 



where 

M 
C 

V 

s 



total flooding quantity, in kg; 
design concentration in percent by 
volume; 

net volume of the hazard, in m^; 
K^ + K^iT), where K^ and K2 are 
constants specific to the agent used 
and r is minimum temperature inside 
enclosure; 



IS 15835 : 2009 



K^ =0.1 825; and 

K^ =0.000 7 

It may also be noted that this equation 
provides an allowance for the normal leakage 
from a tight enclosure to accomplish 
equalization of pressure. 

b) The agent requirement per unit volume of 
protected space can also be calculated by using 
Table 8 for various levels of concentration 
corresponding to the temperature within the 
protected enclosure. (Flooding Factor 
obtained from Table 7 that is temperature of 
the enclosure versus gas concentration, 
multiplied by net volume of the enclosure). 

NOTE — Quantity of the agent shall be the highest of the values 
calculated from the provisions contained in 7.2(a) 
and 7.2(b). 

7,3 The actual quantity of HCFC-125 gas storage 
required shall be determined in the following manner, 
which shall further be subject to changes for pressure 
due to elevation [see 8(f) and Table 8]. 

7.3.1 Enclosure Volumes 

The net enclosure volumes are calculated using the 
following equations: 



a) V^ax = n-K, 
where 



•^Max 



'^Min 



= maximum net volume of the 
enclosure, in m^; 

= gross volume of enclosure, in m^; 

= volume of the structural/similar 
permanent objects in the enclosure 
that gas can not permeate, in m^; 

~ minimum net volume of enclosure 
considering the maximum anticipated 
volume of the occupancy related to the 
objects in the enclosure, in m^; and 

V^ = volume of the occupancy related 
objects in the enclosure that gas can 
not permeate for example, furniture 
fittings etc, in m^; 

(This value shall be ignored if the 
volume is less than 25 percent of the 
maximum net volume Vj^ax)- 

8 DESIGN CONCENTRATION 

a) Determination of design concentration of 
HCFC-125 shall include consideration of the 



Table 7 Total Quantity (HCFC-125) 
(Clause 12) 



SI 


Temper- 


Specific Vapour 


] 


HCFC-12S Mass Requirements per Unit Volume of Protected Space (in kg/ m^ 


) 


No. 


ature 

T 


Volume 

S 

m^/kg 








Design Concentration by Volume 

C 










7 


8 


9 


10 


11 


12 


13 


14 


15 


16 








percent 


percent 


percent 


percent 


percent 


percent 


percent 


percent 


percent 


percent 


i) 


-35 


0.157 


0.478 


0.553 


0.629 


0.706 


0.786 


0.867 


0.950 


1.035 


1.122 


1.211 


ii) 


-30 


0.160 


0.468 


0.540 


0.615 


0.691 


0.768 


0.848 


0.929 


1.012 


1.097 


1.184 


iii) 


-25 


0.164 


0.457 


0.538 


0.601 


0.675 


0.751 


0.829 


0.908 


0.989 


1.072 


1.157 


iv) 


-20 


0.168 


0.447 


0.517 


0.588 


0.660 


0.734 


0.810 


0.888 


0.967 


1.049 


1.132 


V) 


-15 


0.171 


0.437 


0.505 


0.575 


0.646 


0.719 


0.793 


0.869 


0.947 


1.026 


1.108 


vi) 


-10 


0.175 


0.428 


0.495 


0.563 


0.633 


0.704 


0.777 


0.851 


0.927 


L005 


1.085 


vii) 


-5 


0.179 


0.420 


0.485 


0.552 


0.620 


0.690 


0.761 


0.834 


0.908 


0.985 


1.063 


viii) 





0.182 


0.411 


0.475 


0.541 


0.607 


0.676 


0.746 


0.817 


0.890 


0.965 


1.042 


ix) 


5 


0.186 


0.403 


0.466 


0.530 


0.596 


0.663 


0.731 


0.801 


0.873 


0.946 


1.021 


X) 


10 


0.190 


0.396 


0.457 


0.520 


0.584 


0.650 


0.717 


0.786 


0.856 


0.928 


1.002 


xi) 


15 


0,193 


0.389 


0.449 


0.511 


0.574 


0.638 


0.704 


0.772 


0.841 


0.912 


0.984 


xii) 


20 


0.197 


0.381 


0.441 


0.501 


0.563 


0.627 


0.691 


0.758 


0.825 


0.895 


0.966 


xiii) 


25 


0.200 


0.375 


0.433 


0.492 


0.553 


0.615 


0.679 


0.744 


0.811 


0.879 


0.949 


xiv) 


30 


0.204 


0.368 


0.425 


0.484 


0.544 


0.605 


0.667 


0.731 


0.797 


0.864 


0.932 


xv) 


35 


0.207 


0.362 


0.418 


0.475 


0.534 


0.594 


0.656 


0.719 


0.783 


0.849 


0.916 


xvi) 


40 


0.211 


0.356 


0.411 


0.468 


0.525 


0.584 


0.645 


0.707 


0.770 


0.835 


0-901 


xvii) 


45 


0.214 


0.350 


0.404 


0.460 


0.517 


0.575 


0.634 


0.695 


0.757 


0.821 


0.886 


xviii) 


50 


0.218 


0.344 


0.398 


0.452 


0.508 


0.565 


0.624 


0.684 


0.745 


0.808 


0.872 


xix) 


55 


0.221 


0.339 


0.391 


0.445 


0.500 


0.557 


0.614 


0.673 


0.733 


0.795 


0.858 


xx) 


60 


0.225 


0.333 


0.385 


0.438 


0.493 


0.548 


0.605 


0.662 


0.722 


0.782 


0.845 


xxi) 


65 


0.228 


0.328 


0.379 


0.432 


0.485 


0.540 


0.595 


0.652 


0.711 


0.771 


0.832 


xxii) 


70 


0.232 


0.323 


0.374 


0.425 


0.478 


0.531 


0.586 


0.643 


0.700 


0.759 


0.819 


xxiii) 


75 


0.235 


0.319 


0368 


0.419 


0.471 


0.524 


0.578 


0.633 


0.690 


0.748 


0.807 


xxiv) 


80 


0.239 


0.314 


0.363 


0.413 


0.464 


0.516 


0.569 


0.624 


0.680 


0.737 


0.796 


xxv) 


85 


0.242 


0.310 


0.358 


0.407 


0.457 


0.509 


0.561 


0.615 


0.670 


0.726 


0.784 


xxvi) 


90 


0.246 


0.305 


0.353 


0.401 


0.451 


0.501 


0.553 


0.606 


0.660 


0.716 


0.773 


xxvii) 


95 


0.249 


0.301 


0.348 


0.395 


0.444 


0.494 


0.545 


0.598 


0.651 


0.706 


0.762 



IS 15835 : 2009 



type and quantity of combustibles involved, 
the conditions under which it normally exists 
in the enclosure, and any special conditions 
in the enclosure. The HCFC-125 system 
design shall be capable of establishing 
uniform design concentration throughout the 
protected volume, 

b) The distribution system for applying HCFC- 
125 to enclosed hazards shall be designed 
with due consideration of the material^ 
involved, the type of burning expected and 
the nature of the enclosure, any one of which 
may affect the discharge times and rates of 
application. 

c) The minimum design concentration of HCFC- 
125 for fires involving surface Class A fuels, 
and also fires involving flammable Hquids and 
gases shall be as follows: 

1) The minimum design concentration of 
the HCFC- 1 25 agent for Class A surface 
fire hazards shall be the extinguishing 
concentration (6.6) for such fuels plus a 
20 percent safety factor (that is 8 
percent). 

2) The minimum design concentration of 
the HCFC-125 agent for Class B fuel 
hazards shall be the Heptane cup burner 
extinguishing concentration (8.6 percent) 
plus 30 percent safety factor (that is 1 1 .3 
percent). 

3) The minimum design concentration of 
the HCFC-125 agent for Class C, 
electrical/electronic hazards shall be the 
extinguishing concentration for Class A 
surface fires (6.6) plus 20 percent safety 
factor as stated in 8(c) (1), 

NOTE — Where different classes of hazards exist, 
design concentration shall be for the hazard requiring 
the greatest concentration. 

d) Requirements for Flame Extinguishments — 
For Class B fuels other than Heptane, tests 
shall be conducted in independent 
recognized laboratories for the determination 
of extinguishing concentration. This value 
as determined shall be loaded by a safety 
factor of 30 percent. In no case, shall the 
design concentration be less than the 
extinguishing concentration plus a loading 
factor of 20 percent that is 8 percent or such 
higher figure, determined by test as indicated 
above. 

NOTE — Where a range of fuels are present, design 
concentration shall be for the fuel requiring the highest 
concentration as determined in independent recognized 
laboratories. 



e) Lastly, it is required to adjust the number of 
HCFC-125 agent containers, where necessary, 
by compensating for ambient pressure change 
due to location elevation as per Table 8 and 
round off the number as before. The equation 
in such cases will be as follows: 

1) A^i = //^atmospheric correction factor 

2) A^j = adjusted number of containers 

3) N = initial number of containers 

f) Atmospheric Correction Factors — It shall be 
necessary to adjust the actual HCFC-125 
agent quantity for altitude effects. Depending 
upon the altitude, atmospheric correction 
factor shall be applied as per the Table 8. The 
adjusted HCFC-125 agent quantity is 
determined by multiplying the number of 
HCFC-125 containers by the ratio of average 
ambient enclosure pressure to standard sea 
level pressure. 

Table 8 Atmospheric Correction Factors 



SI No. 


Equivalent 


Enclosure 


Atmospheric 




Altitude 


Pressure 


Correction Factor 




m 


mmHg 




(1) 


(2) 


(3) 


(4) 


i) 


-920 


840 


1.11 


ii) 


H510 


812 


1.07 


iii) 


-300 


787 


1.04 


iv) 





760 


1.00 


V) 


300 


733 


0.96 


vi) 


610 


705 


0.93 


vii) 


920 


678 


0.89 


viii) 


1220 


650 


0.86 


ix) 


1520 


622 


0.82 


X) 


1830 


596 


0.78 


xi) 


2 130 


570 


0.75 


xii) 


2 440 


550 


0.72 


xiii) 


2 740 


528 


0,69 


xiv) 


3 050 


505 


0.66 



9 POST DISCHARGE SCENARIO 

The HCFC-125 system shall be, when tested for 
discharge test, in accordance with the following 
requirements: 

a) Within 1 min of commencement of discharge, 
the concentrations at not more than 1 m above 
the floor of the enclosure or at the top of the 
highest hazard shall not vary from the design 
concentration by more than 1 percent by 
volume. 

b) At 10 min of the discharge or other period 
(as required if necessary), the concentrations 
at the levels given in item (a) shall be not 
less than 80 percent of the design 
concentration. 



IS 15835 : 2009 



10 APPLICATION RATE, DURATION OF 
DISCHARGE AND DISCHARGE TIME 

10.1 Design Application Rate 

The design application rate shall be based on the 
quantity of HCFC-125 as per 7,2(a) and the duration 
of discharge required under 9(b). 

10o2 Duration of HCFC-125 Discharge 

The minimum theoretical injected concentration shall 
be achieved within 10 s and the actual injected 
concentration (that is the above plus a suitable safety 
factor adjusted for container rounding ofif) shall be 
achieved within 2 min. 

10.3 Discharge Time for the HCFC-125 Gas 

The discharge time shall be the time for actuation of 
the first HCFC- 1 25 container valve to the achievement 
of the required design concentration or the discharge 
time is the interval from the first appearance of liquid 
at the nozzle to the time when the discharge becomes 
predominantly gaseous, recognized by a change in 
the appearance and sound of the discharge. Although, 
a discharge time of 10 s is considered adequate to 
normal surface burning fires, where the fire may 
spread faster than normal, or where high volumes or 
vital machinery or equipment are involved, higher 
rates shall be used. 

a) The discharge time period is defined as the 
time required to discharge from the nozzles 
90 percent of the agent mass at 21''C, 
necessary to achieve the minimum design 
concentration based on a 20 percent safety 
factor for flame extinguishment. 

b) The discharge time required to achieve 
90 percent of the minimum design concentration 
for flame extinguishment based on a 20 percent 
safety factor shall not exceed 10 s. 

c) How calculations performed in accordance with 
13, or in accordance with the listed pre- 
engineered systems, shaU be used to demonstrate 
the discharge time requirements stated above. 

d) When an extended discharge is desired to 
maintain the design concentration for the 
specified period of time, additional quantities 
of agent can be applied at a reduced rate. The 
initial discharge shall be completed within the 
limits as specified above. Performance of the 
extended discharge shall be demonstrated by 
test. 

11 STORAGE CONTAINERS 

The HCFC-125 storage containers shall comply with 
the following in addition to various requirements 
contained in IS 15493: 



a) The containers used in HCFC-125 systems 
shall be seamless cylinders designed, 
fabricated, inspected, certified and stamped 
in accordance with the requirements of Chief 
Controller of Explosives, Nagpur. 

b) The design pressure shall be suitable for 
the maximum pressure developed at 65''C 
or at the maximum controlled temperature 
limit. 

c) The containers shall be charged to a filling 
ratio (fill density) not greater than 930 kg/m^ 
(0.93 kg/litre) and not less than 480 kg/m^ 
(0.48 kg/litre). 

d) The containers shall be super-pressurized with 
nitrogen (moisture content not greater than 
0.005 percent by volume) to a total pressure 
of either 2.5 MPa ± 5 percent or at 4.2 MPa ± 
5 percent measured at 21 ± FC. 

e) The storage containers shall have reliable 
means of indicating their pressure. 

f) The storage containers shall have reliable 
means of indicating the variation of container 
pressure with temperature. A pressure/ 
temperature chart {see Fig. 1 and 2) attached 
to the container, is acceptable. 

g) The requirements of authorities having 
jurisdiction for containers may take 
precedence over the requirements of this 
standard, if their specifications are more 
stringent. 

12 DISTRIBUTION SYSTEM 

The HCFC-125 distribution system shall comply with 
the following in addition to various requirements 
contained in IS 15493. 

12,1 Piping Network 

a) The piping shall withstand the maximum 
expected pressure at the maximum storage 
temperature, as follows: 

1) 2.5 MPa systems — 4.19 MPa at 55X; 
and 

2) 4.2 MPa systems — 6.58 MPa at 55X. 

b) Carbon steel pipes and fittings shall be 
galvanized inside and outside or otherwise 
suitably protected against corrosion. Stainless 
steel pipes and fittings may be used without 
corrosion protection, 

c) The piping shall withstand the maximum 
developed pressure at 55°C and shall be in 
accordance with IS 15493. 

NOTE — Stainless steel pipes may be used in all applications 
subject to appropriate design strength calculations. 



IS 15835 : 2009 



12.2 Piping Fittings 

a) Pipe fittings shall comply with the 
requirements given in IS 15493. 

b) Fittings shall be selected according to the wall 
thickness or schedule number of the pipe to 
which they are intended to be fitted. 

12.3 Pipe Sizing 

Pipe sizing is a complex issue, particularly in view of 
the two-phase flow within the pipe lines. Too small a 
bore results in excessive pressure losses while too lai-ge 
a bore reduces the liquid flow velocity. This also may 
result in excess pressure drops and lower flow rates. 
Table 9 may be used as a guide to estimate pipe sizes. 
The sizes can be checked using an approved computer 
flow calculation programme. 

Table 9 Pipe Sizes versus Flow Rate (Informative) 



SI No. 


Nominal 


Minimum 


Maxim 


lum Flow Rate for 




Bore 


Flow 


Equivalent Lengths of Pipe 






Rate 










mm 


kg/s 




kg/s 






r 




^ 








More 


Between 


Up to 








than 


5 and 


5m 








10m 


10m 




(1) 


(2) 


(3) 


(4) 


(5) 


(6) 


i) 


10 


0.3 


0.3 


0.4 


0.5 


ii) 


15 


0.5 


0.5 


0.7 


1.0 


iii) 


20 


1.0 


1.0 


1.0 


2.0 


iv) 


25 


1.5 


1.5 


2.7 


4.0 


V) 


32 


2.6 


3.5 


5.6 


8.0 


vi) 


40 


3.8 


4.5 


8.6 


12.2 


vii) 


50 


5.9 


8.8 


16.3 


23.5 


viii) 


65 


8.8 


14.5 


25.4 


37.0 


ix) 


80 


15.0 


25.0 


45.0 


63.5 


X) 


100 


26.3 


50.0 


90.0 


131.5 


xi) 


125 


43.0 


95.0 


172.0 


250.0 


xii) 


150 


57.5 


150.0 


272.0 ' 


408.0 



12,4 Nozzle Placement 

a) The type of nozzles selected, their number and 
placement shall be such that the design 
concentration will be established in all parts 
of the protected enclosure and such that the 
discharge will not unduly splash flammable 
liquids or create dust clouds that could extend 
the fire, create an explosion, or otherwise 
adversely affect the contents or the integrity 
of the enclosure. 

b) Selecting the number of nozzles in a system 
shall take into account, the shape of the 
enclosure (Area and volume), shape of the 
void (Raised floor, suspended ceiling), 
installed equipment in the enclosure/void 
(Chimney effect), allowed pressure at the 
restrictor (Pipe quality) and obstructions, 



which may affect the distribution of the 
discharged agent and architectural 
considerations. 

c) Nozzles shall be selected and located to 
protect an area less than its area of coverage. 
The area of coverage to the type of nozzle 
shall be so listed for the purpose. 

d) In hazards having suspended ceiling, 
consideration shall be given for having 
nozzles installed in the ceiling void 
(simultaneous discharge) in order to equalize 
the pressure during discharge, thus reducing 
the risk of unnecessary damaging ceiling tiles 
etc, 

e) In hazards having raised floor (not gas tight) 
consideration shall be given for having 
nozzles installed in the floor void 
(simultaneous discharge) in order to equalize 
the pressure and obtain extinguishing 
concentration below the floor. 

f) In hazards having suspended ceiling, nozzles 
for protecting rooms shall be installed in such 
a way that the jets from the nozzles do not 
damage the ceiling plates excessively during 
discharge, that is the nozzles to be positioned 
vertically with the discharge holes free of the 
ceiling tiles and/or escutcheon plates. For light 
weight ceiling tiles, it may be recommended 
to securely anchor tiles for a minimum 
of 1.5 m from each discharge nozzle. 

g) Maximum nozzle height above floor level for 
a single row of nozzles is 4. 1 m. Where ceiling 
height (of the protected enclosure) exceed 
4,1 m, an additional row of nozzles shall be 
provided for uniform and faster distribution 
of the agent within the enclosure. 

h) Minimum nozzle height above the floor level 
of the hazard shall be 46 m. 

j) The maximum distance between nozzles 
should not exceed 6 m and the maximum 
distance to wall/partition should not exceed 
3 m. 

k) In case of enclosures having no false ceiling, 
nozzles can be located on the ceiling 
anywhere within 0.5 m to 5 m from the walls 
In case of enclosures having false ceilings, 
deflector shields shall be used with each 
nozzle and also nozzles shall be so located 
(with an anticipation of dislodgement of false 
ceiling materials cr any movable objects in 
the path of discharge) to prevent any damage 
thereto. 

m) Nozzles shall be provided in all the concealed 
spaces, floor voids, ceiling voids etc besides 
the main area within the protected enclosure. 



IS 15835 : 2009 



13 HYDRAULICS OF THE SYSTEM 

13.1 General 

a) An approved hydraulic calculation method 
shall be employed to predict pipe sizes, nozzle 
pressure, agent flow rate, discharge per nozzle 
and the discharge time. 

b) The various parameters as stated below shall 
be considered to determine the following 
minimum limits of accuracy: 

1) The weight of agent predicted by flow 
calculation to discharge from the nozzle 
should agree with the total weight of 
agent actually discharged from each 
nozzle in the system within a range of 
-5 percent to +10 percent of actual 
prediction. 

2) The discharge time predicted by the flow 
calculation method should agree with the 
actual discharge time from each nozzle 
in the system. 

3) The accuracy of the calculated nozzle 
pressures versus actual pressures at each 
nozzle should be such that actual nozzle 
pressures in an installation will not fall 
outside the range required for acceptable 
nozzle performance. 

4) The nozzle pressure should not fall below 
the minimum or above the maximum 
nozzle pressure required for the nozzle 
to uniformly distribute the agent 
throughout the volume which that 
nozzle's discharge is to protect. 



13.2 Two-Phase Flow of HCFC-125 

5^^ Annex E of IS 15493. 

13.3 Engineered and Pre-engineered Systems 

a) General — HCFC-125 is suitable for use in 
both engineered (central storage) systems and 
pre-engineered (modular or packaged) 
systems, as described in 13.3(b) and 13.3(c). 

b) Engineered — An engineered system uses 
large storage containers installed in a central 
location. The containers are manifold together 
and a single pipe feeds the nozzle located 
inside the hazard area. Predicting pipe 
pressure losses and designing nozzle orifice 
sizes requires complex flow calculations for 
both HCFC-125 and nitrogen phases, which 
takes into account the minimum and 
maximum volumes or the enclosure. 

c) Pre-engineered — A pre-engineered system 
involves a single container with a maximum 
of two nozzles and a small piping network. 
This system can be multiplied to cover larger 
volume areas. The larger area is viewed as a 
number of smaller areas each protected by a 
single modular unit. 

14 COMMISSIONING AND ACCEPTANCE 
TESTING 

14,1 Criteria for Acceptance 

The completed HCFC-125 total flooding system shall 
be commissioned in accordance with 9 of IS 15493 
and the system's performance proved. 



MGIPF— 956 B)S/08~4.3.0&-300 Books.